forked from OSchip/llvm-project
168 lines
5.9 KiB
C++
168 lines
5.9 KiB
C++
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//===-- BPFMCCodeEmitter.cpp - Convert BPF code to machine code -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements the BPFMCCodeEmitter class.
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//
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/BPFMCTargetDesc.h"
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#include "llvm/MC/MCCodeEmitter.h"
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#include "llvm/MC/MCFixup.h"
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#include "llvm/MC/MCInst.h"
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#include "llvm/MC/MCInstrInfo.h"
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#include "llvm/MC/MCRegisterInfo.h"
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#include "llvm/MC/MCSubtargetInfo.h"
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#include "llvm/MC/MCSymbol.h"
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#include "llvm/ADT/Statistic.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DEBUG_TYPE "mccodeemitter"
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namespace {
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class BPFMCCodeEmitter : public MCCodeEmitter {
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BPFMCCodeEmitter(const BPFMCCodeEmitter &) LLVM_DELETED_FUNCTION;
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void operator=(const BPFMCCodeEmitter &) LLVM_DELETED_FUNCTION;
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const MCRegisterInfo &MRI;
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public:
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BPFMCCodeEmitter(const MCRegisterInfo &mri) : MRI(mri) {}
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~BPFMCCodeEmitter() {}
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// getBinaryCodeForInstr - TableGen'erated function for getting the
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// binary encoding for an instruction.
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uint64_t getBinaryCodeForInstr(const MCInst &MI,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const;
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// getMachineOpValue - Return binary encoding of operand. If the machin
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// operand requires relocation, record the relocation and return zero.
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unsigned getMachineOpValue(const MCInst &MI, const MCOperand &MO,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const;
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uint64_t getMemoryOpValue(const MCInst &MI, unsigned Op,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const;
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void EncodeInstruction(const MCInst &MI, raw_ostream &OS,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const override;
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};
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}
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MCCodeEmitter *llvm::createBPFMCCodeEmitter(const MCInstrInfo &MCII,
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const MCRegisterInfo &MRI,
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const MCSubtargetInfo &STI,
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MCContext &Ctx) {
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return new BPFMCCodeEmitter(MRI);
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}
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unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI,
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const MCOperand &MO,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const {
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if (MO.isReg())
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return MRI.getEncodingValue(MO.getReg());
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if (MO.isImm())
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return static_cast<unsigned>(MO.getImm());
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assert(MO.isExpr());
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const MCExpr *Expr = MO.getExpr();
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MCExpr::ExprKind Kind = Expr->getKind();
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assert(Kind == MCExpr::SymbolRef);
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if (MI.getOpcode() == BPF::JAL)
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// func call name
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Fixups.push_back(MCFixup::Create(0, Expr, FK_SecRel_4));
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else if (MI.getOpcode() == BPF::LD_imm64)
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Fixups.push_back(MCFixup::Create(0, Expr, FK_SecRel_8));
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else
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// bb label
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Fixups.push_back(MCFixup::Create(0, Expr, FK_PCRel_2));
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return 0;
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}
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// Emit one byte through output stream
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void EmitByte(unsigned char C, unsigned &CurByte, raw_ostream &OS) {
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OS << (char)C;
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++CurByte;
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}
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// Emit a series of bytes (little endian)
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void EmitLEConstant(uint64_t Val, unsigned Size, unsigned &CurByte,
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raw_ostream &OS) {
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assert(Size <= 8 && "size too big in emit constant");
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for (unsigned i = 0; i != Size; ++i) {
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EmitByte(Val & 255, CurByte, OS);
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Val >>= 8;
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}
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}
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// Emit a series of bytes (big endian)
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void EmitBEConstant(uint64_t Val, unsigned Size, unsigned &CurByte,
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raw_ostream &OS) {
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assert(Size <= 8 && "size too big in emit constant");
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for (int i = (Size - 1) * 8; i >= 0; i -= 8)
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EmitByte((Val >> i) & 255, CurByte, OS);
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}
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void BPFMCCodeEmitter::EncodeInstruction(const MCInst &MI, raw_ostream &OS,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const {
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unsigned Opcode = MI.getOpcode();
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// Keep track of the current byte being emitted
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unsigned CurByte = 0;
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if (Opcode == BPF::LD_imm64) {
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uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
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EmitByte(Value >> 56, CurByte, OS);
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EmitByte(((Value >> 48) & 0xff), CurByte, OS);
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EmitLEConstant(0, 2, CurByte, OS);
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EmitLEConstant(Value & 0xffffFFFF, 4, CurByte, OS);
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const MCOperand &MO = MI.getOperand(1);
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uint64_t Imm = MO.isImm() ? MO.getImm() : 0;
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EmitByte(0, CurByte, OS);
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EmitByte(0, CurByte, OS);
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EmitLEConstant(0, 2, CurByte, OS);
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EmitLEConstant(Imm >> 32, 4, CurByte, OS);
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} else {
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// Get instruction encoding and emit it
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uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
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EmitByte(Value >> 56, CurByte, OS);
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EmitByte((Value >> 48) & 0xff, CurByte, OS);
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EmitLEConstant((Value >> 32) & 0xffff, 2, CurByte, OS);
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EmitLEConstant(Value & 0xffffFFFF, 4, CurByte, OS);
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}
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}
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// Encode BPF Memory Operand
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uint64_t BPFMCCodeEmitter::getMemoryOpValue(const MCInst &MI, unsigned Op,
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SmallVectorImpl<MCFixup> &Fixups,
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const MCSubtargetInfo &STI) const {
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uint64_t Encoding;
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const MCOperand Op1 = MI.getOperand(1);
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assert(Op1.isReg() && "First operand is not register.");
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Encoding = MRI.getEncodingValue(Op1.getReg());
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Encoding <<= 16;
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MCOperand Op2 = MI.getOperand(2);
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assert(Op2.isImm() && "Second operand is not immediate.");
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Encoding |= Op2.getImm() & 0xffff;
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return Encoding;
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}
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#include "BPFGenMCCodeEmitter.inc"
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